What is the possessive form of the plural noun needed in the sentence?

The correct answer is “children’s” because it represents the possessive form of the plural noun “children.” In English, when forming the possessive of a plural noun that ends in "s," you typically add an apostrophe after the "s." Therefore, for the noun "children," which is already plural, the possessive form is created by adding an apostrophe after the "n," thus resulting in "children’s." This structure indicates that something belongs to or is associated with children.

The other choices do not correctly express the possessive form for a plural noun. "Children" simply indicates the plural form without possession, "childs" is not a standard form in English, and "child's" is the possessive form of the singular noun "child," referring to something belonging to one child. These distinctions clarify why "children’s" is the appropriate choice in this context.